Why did Japan invaded China?
Japan is a resource-poor country. They wanted China's resources. It was the same with Pearl Harbor. At the time, the U.S. was the world's largest oil producer. In response to Japanese outrages in China and elsewhere, the U.S. cut off exports of oil and steel to Japan. That was really an act of war, because without oil, Japan would be out of business. The Japanese decided to seize the oil fields in the Dutch East Indies, now part of Indonesia. As a precaution they sank the American fleet at Pearl Harbor first. Japan's actions in China and the Pacific War must be seen in light of their views of their own racial superiority.